Complete power management system implemented in a single surface mount package

ABSTRACT

A complete power management system implemented in a single surface mount package. The system may be drawn to a DC to DC converter system and includes, in a leadless surface mount package, a driver/controller, a MOSFET transistor, passive components (e.g., inductor, capacitor, resistor), and optionally a diode. The MOSFET transistor may be replaced with an insulated gate bipolar transistor, IGBT in various embodiments. The system may also be a power management system, a smart power module or a motion control system. The passive components may be connected between the leadframe connections. The active components may be coupled to the leadframe using metal clip bonding techniques. In one embodiment, an exposed metal bottom may act as an effective heat sink.

RELATED APPLICATIONS

This Application claims benefit of U.S. Provisional Patent ApplicationSer. No. 60/696,037, filed Jul. 1, 2005, entitled “Complete PowerManagement System Implemented Using Leadless Surface Mount Package withExposed Metal Bottom” to Owyang et al., which is hereby incorporatedherein by reference in its entirety.

This Application is related to U.S. Pat. No. 6,066,890, issued May 23,2000, entitled “Separate Circuit Devices in an Intra-PackageConfiguration and Assembly Techniques,” to Tsui and Kasem, which ishereby incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Embodiments of the present invention are directed toward the field ofintegrated circuit devices and packaging related to power managementsystems.

2. Related Art

Varieties of integrated circuits are commercially available tofacilitate power management tasks, for example, to control DC to DCvoltage conversion or as a constant current controller.

DC/DC converter circuits are commonly used as Point Of Load (POL) powersources to drive a wide variety of semiconductor devices from a single“bulk” voltage routed around a system, for example, in an intermediatebus architecture (IBA). Generally, POL converter circuits are placedright alongside each semiconductor device and shift a single IBA voltageto the different voltage levels required by each integrated circuit.Typically, DC/DC converters drive such devices as FPGAs,microprocessors, DSPs, ADCs, SDRAMs, up/down converters, etc.

DC/DC converter circuits are also frequently used in systems comprisingrechargeable batteries. Theses applications are characterized byportability (size, weight, etc.) and length of service from a singlecharge. For example, the efficiency of the DC/DC converter circuitdirectly affects the standby and talk time available from a cell phonebetween battery charges.

Current control products generally fall into two categories: constantcurrent controllers and constant current sources. A constant currentcontroller accepts a constant DC voltage and converts it to a constantcurrent output. When the input voltage is subject to variation orinstability a DC/DC converter is first used to steady the DC voltage andthen the constant current controller takes that steady voltage and putsout a constant current. A constant current source generally comprises aDC/DC converter and a constant current controller.

DC/DC converters and current controllers offered by many integratedcircuit (IC) manufacturers are silicon chips that provide only the basicoperation for circuit functions. An end user must then select up toabout 22 other components that surround the integrated circuit in orderto create a complete circuit solution. The selection of these componentsand the circuit board layout affect the final performance in suchcritical areas as efficiency, ripple voltage, reliability, etc.Unfortunately, these critical features as defined by the integratedcircuit manufacturer may not be the same as the performance featuresachieved when the customer completes the circuit on the board with theaddition of external components. Consequently, because the user'sassemblage of parts does not become a complete circuit function untilthe first time all parts come together, e.g., on a printed circuitboard, the function must be tested as a subsystem function on the board.

Vishay Intertechnology, Inc., of Malvern, Pa., currently offers severalversions of the FunctionPAK® DC/DC converters and current controlmodules. FunctionPAK® products are complete power management systems insingle surface mount, e.g., BGA, packages. Advantageously, this productis a complete power management function in a single module. The singlepackage contains all circuit components and is fully tested with allcircuit parameters defined exactly as used in the customer's system.

FunctionPAK® power management products generally comprise multi-chipmodule (MCM) circuit packaging. In general, the term MCM refers to apackage comprising two or more circuit elements, usually including atleast one integrated circuit, and an interconnecting substrate to couplethe circuit elements and the package contacts. MCM devicesconventionally include, for example, laminated substrates, e.g., FR4printed circuit boards, thin film depositions, surface laminar circuitry(SLC) and/or ceramic substrates.

FIG. 1A illustrates a top view of an exemplary MCM comprising manyseparate chip devices, passive components and other items mounted on amultilayer printed circuit board (PCB). For example, the exemplary MCMcomprises an integrated circuit device 1, an inductor 2, a plurality ofpassive components, e.g., resistors and/or capacitors, 3, and amultilayer printed circuit board (PCB) 4. The devices and printedcircuit board can be molded in plastic producing a single package. FIG.1A also shows a side sectional view of components molded in plasticencapsulant 5.

FIG. 1B illustrates another top view of an exemplary MCM.

FIG. 1C illustrates a bottom view of an exemplary PCB for use in amulti-chip module that utilizes a ball grid array (BGA) packagingtechnique. FIG. 1C illustrates an exemplary ball grid array ball 6, usedas a package contact to couple circuitry of the multi-chip module to anext electronic assembly, e.g., other components mounted to a processor“mother” board. FIG. 1C illustrates an exemplary wiring trace 7, whichserves to couple the various components of the MCM and the packagecontacts, e.g., “balls.”

FunctionPAK® or MCM provides complete solutions and offers manyadvantages, e.g., the MCM saves space and weight, simplifies end productdesign/development, reduces component count, reduces assembly costs andsaves test time, and speeds time-to-market.

The current FunctionPAK® power management products based on MCM designmay, in some instances, have several electrical and thermal limitationsas follows: 1) undesirable parasitic resistance due to thin copperlayer; 2) undesirable parasitic inductance due to the pins of thepackage; limited current carrying capacity; 3) undesirable decreasedefficiency due to the combined effects from the parasitic and the poorthermal performance; 4) undesirable power density because packagedsilicon devices (control driver and power MOSFETs) are used which areencapsulated in a poor thermal conductive mold material; 5) undesirableswitching frequency due to high switching loss, which limits theoperating temperature and current rating; and 6) undesirable thermalperformance due to poor thermal conductivity of the materials used. Inaddition, the design of the FunctionPAK® MCM using a multilayer PCB as asubstrate with BGA re-routed connections may provide poor thermalefficiency and poor heat sinking. As a result, the operation andreliability of the circuit and active devices can be impacted. Asdiscussed above, when the MCM is molded in plastic, the heat dissipationelements of each individual component become rendered ineffective.

FIG. 2A illustrates another design that utilizes surface mountcomponents (mounted on copper) for a MOSFET device (high side 11 and lowside 12) and a driver/controller 10 for a DC to DC converter system.However, this solution is not a complete power management system, as itdoes not include the passive components required in such a system.

FIG. 2B illustrates the packaged top side 20 of the design of FIG. 2Aand an x-ray view 30 from the same perspective.

FIG. 2C illustrates a package mechanical drawing of the design of FIGS.2A and 2B. Package bottom view 34 illustrates the metal bottom, or leadframe, used has a heat sink (31, 32 and 33). Unfortunately, this designdoes not provide a complete system solution because the passivecomponents required for a complete design are not included.

SUMMARY OF THE INVENTION

Accordingly, a complete power management system is described herein andis implemented using a surface mount package. The system may be drawn toa DC to DC converter system and includes, in a surface mount package, adriver/controller, a MOSFET transistor, passive components (e.g.,inductor, capacitor, resistor), and optionally a diode. The MOSFETtransistor may be replaced with an insulated gate bipolar transistor,IGBT, in various embodiments. The system may also be a power managementsystem, a smart power module, a current controller or a motion controlsystem. The passive components may be connected between the leadframeconnections. The active components may be coupled to the leadframe usingmetal clip bonding techniques. In one embodiment, an exposed metalbottom may act as an effective heat sink.

The advantages of using the surface mount packaging include highercurrent rating, reduced parasitic effects and higher efficiency. Inaddition, the embodiments of the present invention offer higher powerdissipation, lower thermal resistance and a smaller footprint on a nextlevel assembly. Embodiments also offer lower assembly cost.

According to embodiments of the present invention, a standard surfacemount package (SMP) is used with exposed metal bottom. The package mayemploy a copper lead frame to replace a multilayer FR4 substratematerial (PCB) and the BGA connections. As a result, the assemblyprocess is simplified and the product cost is reduced. In addition andthe performance and reliability of the DC-DC converter is greatlyenhanced.

The use of SMP has many advantages. The copper lead frame in the packageis much thicker than that used in the MCM FunctionPAK®. Therefore, theparasitic resistance is significantly reduced compared to theconventional FunctionPAK®. Another advantage is to use metal (e.g.,copper) clips on the source and drain of the MOSFET that improve thermaland electrical performance of the MOSFET. The metal clips can also beused on the diode. Also, SMP can handle much more current than MCMFunctionPAK®, because higher current causes more power loss, whichcannot be dissipated by the high thermal resistivity of MCM FunctionPAK®construction.

Moreover, SMP can produce higher efficiency because it significantlyreduces the parasitic inductance and the related switching loss, and ithas good thermal performance. Also, SMP has higher power density becauseits good thermal performance can dissipate more power and it is morecompact because the silicon dice are packageless. Also, SMP can make thecircuit operate at higher switching frequency because it reduces theswitching loss and it has much lower thermal resistivity.

SMP eliminates the internal packaging requirements of the electricalcomponents. Without the internal package, the bare circuit componentswill have better thermal performance due to the high thermalconductivity of the lead frame and better electrical performance due tothe less parasitic inductance. In addition, SMP can lead to less costbecause there is no need for internal package.

The SMP embodiments can be extended to provide a new integrated platformfor the applications of power MOSFETs, such as power management, smart(intelligent) power modules, DC-DC converters and motion controlsystems, among some exemplary uses.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a non-molded view of the MCM of the prior art.

FIG. 1B is a non-molded view of the MCM of the prior art.

FIG. 1C is a bottom view of the BGA of the MCM of the prior art.

FIG. 2A is a top view of the incomplete system of the prior art usingsurface mount technology.

FIG. 2B is a top view of the prior art design of FIG. 2A.

FIG. 2C is a top and bottom view of the prior art design of FIG. 2A.

FIG. 3A and FIG. 3B illustrate embodiments of the present invention fora complete power management system utilizing leadless surface mountpackaging with metal bottom.

FIG. 4 illustrates the use of metal clip bonding of the activecomponents in accordance with an embodiment of the present invention toimprove electrical and thermal properties of the system.

FIG. 5 illustrates a process for fabrication of the device in accordancewith the present invention.

FIG. 6 illustrates the use of an electrically isolated substrate forgrouping passive components with internal connection in accordance withan embodiment of the present invention.

FIG. 7A and FIG. 7B illustrate plan views of embodiments of the presentinvention.

FIG. 8 illustrates the bottom view of the device in accordance with thepresent invention and illustrates the exposed leadframe configuration.

FIG. 9A illustrates a perspective view of a molded exemplary embodimentof the present invention.

FIG. 9B illustrates a perspective view of a non-molded exemplaryembodiment of the present invention.

FIG. 10A illustrates a plan view of an exemplary embodiment of thepresent invention.

FIG. 10B illustrates a perspective view of a non-molded exemplaryembodiment of the present invention.

FIG. 11A illustrates a perspective view of an exemplary embodiment ofthe present invention.

FIG. 11B illustrates a perspective view of a leadframe configuration ofan exemplary embodiment of the present invention.

FIG. 12A illustrates a perspective view of a leadframe configuration ofan exemplary embodiment of the present invention.

FIG. 12B illustrates a plan view of a leadframe configuration of anexemplary embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to the preferred embodiments of thepresent invention, complete power management system implemented in asingle surface mount package, examples of which are illustrated in theaccompanying drawings. While the invention will be described inconjunction with the preferred embodiments, it will be understood thatthey are not intended to limit the invention to these embodiments. Onthe contrary, the invention is intended to cover alternatives,modifications and equivalents, which may be included within the spiritand scope of the invention as defined by the appended claims.Furthermore, in the following detailed description of the presentinvention, numerous specific details are set forth in order to provide athorough understanding of the present invention. However, it will berecognized by one of ordinary skill in the art that the presentinvention may be practiced without these specific details. In otherinstances, well-known methods, procedures, components, and circuits havenot been described in detail as not to unnecessarily obscure aspects ofthe present invention.

FIG. 3A and FIG. 3B illustrate embodiments of the present invention fora complete power management system 100 utilizing leadless surface mountpackaging with metal bottom. The system may be any power managementapplication, e.g., a DC to DC converter, a constant current controller,a motion control system, or a smart power module, etc. According to theembodiment of FIG. 3A, the system includes a controller/driverintegrated circuit 101, e.g., the integrated circuit portion of theVishay Siliconix Si91966 “High Frequency Programmable TopologyController,” a MOSFET transistor (HiMOS 103 and LoMOS 102), and aplurality of passive components where Cn are capacitors, Ln areinductors and Rn are resistors. Advantageously, the passive componentsare connected between the lead posts of the metal leadframeconfiguration as shown by L1, etc.

For example, inductor L1 is shown disposed between leadframe portion 105and leadframe portion 106. It is to be appreciated that inductor L1 maybe electrically coupled to leadframe portion 105 and leadframe portion106, in accordance with embodiments of the present invention.Optionally, a diode D1 may be connected in a similar manner. Theleadframe may comprise copper or other materials suitable forleadframes, for example, aluminum, gold, and other metals and alloys. Inaccordance with embodiments of the present invention, the lead frame maybe multi-layered.

It is to be appreciated that embodiments in accordance with the presentinvention are well suited to the use of industry standard surface mountpackages for components. For example, resistors and/or capacitors may beprovided in Joint Electron Device Engineering Council (JEDEC) standardpackages, e.g., “0201” or “01005.” Such use of standard componentsoffers numerous advantages, including, e.g., multiple sources andreadily available pick and place technology.

Embodiments of the present invention may connect the passive componentsto the leadframe according to technology described in U.S. Pat. No.6,066,890, entitled “Separate Circuit Devices in an Intra-PackageConfiguration and Assembly Techniques,” issued May 23, 2000 by Tsui etal., which is hereby incorporated by reference. The passive componentsmay be connected between elements of the leadframe in order to reduceparasitic effects, e.g., inductance and/or capacitance, and to savedevice space, e.g., allowing the system to be reduced in size.

Embodiments in accordance with the present invention may utilize metal(e.g., copper) clip bonding 110 for connecting active components to theleadframe. This increases thermal and electrical characteristics of thesystem. The active components include the driver/controller and theMOSFET driver.

It is appreciated that the complete power management system 100 of FIG.3A and FIG. 3B is mounted using a leadless surface mounted packagehaving a metal bottom, in accordance with embodiments of the presentinvention. As described further below, the metal bottom may provide aneffective heat sink for dissipating heat from the system 100. It isfurther appreciated that the MOSFET transistor may be replaced by aninsulated gate bipolar transistor (IGBT), which can be used for motioncontrol systems.

FIG. 4 illustrates a top view of the system and illustrates the use ofmetal clip bonding in accordance with an embodiment of the presentinvention to improve electrical and thermal properties of the system. Asdescribed above, the active components of the system, for example., thedriver/controller, e.g., driver/controller 101 of FIG. 3B, and theMOSFET transistor, e.g., LoMOS 102 of FIG. 3B and/or HiMOS 103 of FIG.3B, may be connected to a leadframe using metal (e.g., copper) clipbonding for improving the electrical and thermal properties of thedevice. FIG. 4 illustrates top portions of metal clips 111, 112, 113,114, 115 and 116. It is appreciated that the components illustrated asconnected via metal clip bonding are obscured.

FIG. 5 illustrates an exemplary process 120 for fabrication of thedevice in accordance with the present invention. Process 120 begins withformation of a leadframe in 121. A leadframe may be formed viaconventional means, e.g., stamping and bending. In 122, the components,including integrated circuit(s) and passive components are placed.

In accordance with embodiments of the present invention, somecomponents, e.g., integrated circuits, may utilize wire bond couplingsto the leadframe and/or other components.

In 123, surface mount couplings are reflowed, e.g., via vapor phase orinfra red processes. In 124, the devices and leadframe are overmoldedwith a plastic encapsulant, forming a single package. In 125, thepackage is laser marked for identification. In 126 excess plastic fromthe molding process, e.g., “flash” from mold seams or “gate” fromplastic injector gates, is removed.

In 127 the exposed portions of the leadframe are plated forenvironmental stability and to increase their solderability for nextlevel assembly. In 128, the packages are singulated. In 129, the devicesare tested. Those devices passing the tests are then packaged 130, e.g.,in tape and reel.

FIG. 6 illustrates the use of an electrically isolated substrate forgrouping passive components with internal connection in accordance withan embodiment of the present invention. In this embodiment, anelectrically isolated substrate 131, e.g., ceramic, may group severalpassive components with internal connections. Such an isolated substratemay then be coupled to portions of the leadframe and/or othercomponents.

FIG. 7A and FIG. 7B illustrate plan views of complete power managementsystem 700 in accordance with embodiments of the present invention. TheMOSFETs 701 are shown in the upper right corner. Inductor 702 is showndirectly mounted to and “spanning” portions of the leadframe. In thisexample, a diode D1 703 is also used. The diode may be connected to theleadframe using the metal (e.g., copper) clip bonding techniques. FIG.7B illustrates an exemplary design with exemplary dimensions.

FIG. 8 illustrates the bottom view of the complete system (usingleadless surface mounted package) in accordance with the presentinvention and illustrates the exposed leadframe configuration 140. Inthis embodiment of the present invention, the exposed leadframe locatedon the bottom of the device acts as an effective heat sink for thermaldissipation.

FIG. 9A illustrates a perspective view of a molded exemplary embodimentof the present invention. In this embodiment, a device 300 comprises thesystem 100 with covering molded plastic packaging. The plastic moldingis shown in outline, illustrating the interior components.

FIG. 9B illustrates a perspective view of a non-molded exemplaryembodiment of the present invention. Complete system 100 is shown withdriver/controller 50, MOSFET transistor, and passive components, R, Land C. The driver/controller 50 is shown coupled to inductor L1. Theother passive components are shown connected to the leadframe.

FIG. 10A illustrates a plan view of an exemplary embodiment of thepresent invention. As shown, complete system 100 comprises passivecomponents (Cn, Ln, Rn) connected across the leadframe and also includesthe driver/controller 50 and the MOSFET transistor.

FIG. 10B illustrates a perspective view of a non-molded exemplaryembodiment of the present invention. As shown, complete system 100comprises passive components (Cn, Ln, Rn) connected across the leadframeand also includes the driver/controller 50 and the MOSFET transistor.

FIG. 11A illustrates a perspective view of an exemplary embodiment ofthe present invention. As shown, complete system 100 comprises passivecomponents (Cn, Ln, Rn) connected across the leadframe and also includesthe driver/controller 50 and the MOSFET transistor.

FIG. 11B illustrates a perspective view of a leadframe configuration ofan exemplary embodiment of the present invention. This illustrates thebottom of the system. The leadframe is metal. The leadframe is used asan effective heat sink for thermal dissipation.

FIG. 12A illustrates a perspective view of a leadframe configuration ofan exemplary embodiment of the present invention with componentsexposed.

FIG. 12B illustrates a plan view of a leadframe configuration of anexemplary embodiment of the present invention. This illustrates thebottom of the system. The leadframe is metal. The leadframe is used asan effective heat sink for thermal dissipation.

The foregoing descriptions of specific embodiments of the presentinvention, complete power management system implemented in a singlesurface mount package, have been presented for purpose of illustrationand description. They are not intended to be exhaustive or to limit theinvention to the precise form disclosed, and obviously manymodifications and variations are possible in light of the aboveteaching. The embodiments were chosen and described in order to bestexplain the principles of the invention and its practical application,to thereby enable others skilled in the art to best utilize theinvention and various embodiments with various modifications as aresuited to the particular use contemplated. It is intended that the scopeof the invention be defined by the Claims appended hereto and theirequivalents.

What is claimed is:
 1. An apparatus comprising: a controller integratedcircuit; a power MOSFET transistor coupled to said controller integratedcircuit; a plurality of passive components comprising at least oneinductor; wherein said controller integrated circuit, said power MOSFETtransistor and said plurality of passive components are functionallycoupled to implement a complete power management system; wherein saidcontroller integrated circuit, said power MOSFET transistor and saidplurality of passive components are mounted to a metal leadframe; andwherein said controller integrated circuit, said power MOSFET transistorand said plurality of passive components are encapsulated in plastic toform a single package.
 2. The apparatus of claim 1 wherein a portion ofsaid metal leadframe is exposed on the back side of said package.
 3. Theapparatus of claim 2 wherein said portion of said metal leadframe isdisposed for thermal coupling to a printed circuit board.
 4. Theapparatus of claim 1 wherein said metal leadframe comprises copper. 5.The apparatus of claim 1 further comprising metal clip bonding.
 6. Theapparatus of claim 4 further comprising metal clip bonding.
 7. Theapparatus of claim 1 wherein said plurality of passive componentsincludes a diode.
 8. The apparatus of claim 1 wherein terminals of saidat least one inductor are directly mounted to and electrically connectedto portions of said leadframe.
 9. The apparatus of claim 1 wherein saidcontroller integrated circuit, said power MOSFET transistor and saidplurality of passive components are functionally coupled vianon-substrate couplings.
 10. The apparatus of claim 1 wherein a portionof said leadframe provides an electrical path coupling terminals of atleast two separate passive components of said plurality of passivecomponents.
 11. The apparatus of claim 10 wherein said at least twoseparate passive components are directly mounted to said portion of saidleadframe.
 12. A power management device comprising: a controllerintegrated circuit; a power MOSFET transistor coupled to said controllerintegrated circuit; a plurality of passive components comprising atleast one inductor; wherein said controller integrated circuit, saidpower MOSFET transistor and said plurality of passive components arefunctionally coupled to implement a complete power management system;wherein further said controller integrated circuit, said power MOSFETtransistor and said plurality of passive components are mounted to ametal leadframe; and wherein further said controller integrated circuit,said power MOSFET transistor and said plurality of passive componentsare encapsulated in plastic to form a single leadless package.
 13. Thedevice of claim 12 wherein a portion of said metal leadframe is exposedon the back side of said package.
 14. The device of claim 13 whereinsaid portion of said metal leadframe is disposed for thermal coupling toa printed circuit board.
 15. The device of claim 12 wherein said metalleadframe comprises copper.
 16. The device of claim 12 furthercomprising metal clip bonding.
 17. The device of claim 15 furthercomprising metal clip bonding.
 18. The device of claim 12 wherein saidplurality of passive components includes a diode.
 19. The device ofclaim 12 wherein terminals of said at least one inductor are directlymounted to and electrically connected to portions of said leadframe. 20.The device of claim 12 wherein said controller integrated circuit, saidpower MOSFET transistor and said plurality of passive components arefunctionally coupled via non-substrate couplings.
 21. The device ofclaim 12 wherein a portion of said leadframe provides an electrical pathcoupling terminals of at least two separate passive components of saidplurality of passive components.
 22. The device of claim 21 wherein saidat least two separate passive components are directly mounted to saidportion of said leadframe.